US Patent 7776240 Injectable hydrogel microspheres from aqueous two-phase system

Injectable hydrogel microspheres are prepared by forming an emulsion where hydrogel precursors are in a disperse aqueous phase and polymerizing the hydrogel precursors. In a preferred case, the hydrogel precursors are poly(ethylene glycol) diacrylate and N-isopropylacrylamide and the continuous phase of the emulsion is an aqueous solution of dextran and a dextran solubility reducer. The microspheres will load protein, e.g., cytokines, from aqueous solution.